Topological magnetic order and superconductivity in EuRbFe<sub>4</sub>As<sub>4</sub>
- Hemmida, M.
- Winterhalter-Stocker, N.
- Ehlers, D.
- Von Nidda, H.
- Yao, M.
- Bannies, J.
- Rienks, E.
- Kurleto, R.
- Felser, C.
- Büchner, B.
- Fink, J.
- Gorol, S.
- Förster, T.
- Arsenijevic, S.
- Fritsch, V.
- Gegenwart, P.
DOIAbstract
We study single crystals of the magnetic superconductor EuRbFe4As4 by magnetization, electron spin resonance (ESR), angle-resolved photoemission spectroscopy, and electrical resistance in pulsed magnetic fields up to 63 T. The superconducting state below 36.5 K is almost isotropic and is only weakly affected by the development of Eu2+ magnetic order at 15 K. On the other hand, for the external magnetic field applied along the c axis the temperature dependence of the ESR linewidth reveals a Berezinskii-Kosterlitz-Thouless topological transition below 15 K. This indicates that Eu2+ planes are a good realization of a two-dimensional XY magnet, which reflects the decoupling of the Eu2+ magnetic moments from superconducting FeAs layers. © 2021 A...
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